login page refreshes to blank login page

[jarnold]

The shop worked for a long time. If I want to login into the BO or as customer into the shop the login name and the password seems to be accepted but the page is reloaded with a blank login page. If I enter a wrong password it shows an error. The funktion password restore still works but at the login page the same happens.
I have tried to clear the cache without success. I turned on the debug mode, but no error shown. Does anybody has an idea?

Prestashop 8.1.3

[jarnold]

Somehow after 2 days without doing anything else I am able to login again. Does anybody has an idea why this is happen and how to prevent it in future?

[jarnold]

Now it happens again. Same problem, after enter the user and password the login page refreshes. If I am entering a wrong user or password an error message is shown. Does anybody has an idea? Is there any other option to enter the BO (using the token, manipulation in the database,....)?

[Knowband Plugins]

Check in incognito. it should work (If details are correct)

What about the Forgot password option if the login details are not working?

[jarnold]

What is the incognito mode?  The forgot password option creates a new passwort but the result is the same. The login page shows no error but refreshes to a blank login page.

[jarnold]

As you can see in the first post, the version is 8.1.3. Not the newest. The last upgrade I did 1 year ago. Until the end of this January it was working without problems.